A polynomial algorithm for b-matchings: an alternative approach
Information Processing Letters
The traveling salesman problem with distances one and two
Mathematics of Operations Research
Polynomial time approximation schemes for Euclidean traveling salesman and other geometric problems
Journal of the ACM (JACM)
A lower bound on the number of Hamiltonian cycles
Discrete Mathematics
Approximation algorithms for lawn mowing and milling
Computational Geometry: Theory and Applications
Vertex-unfoldings of simplicial manifolds
Proceedings of the eighteenth annual symposium on Computational geometry
Hamiltonian Cycles in Solid Grid Graphs
FOCS '97 Proceedings of the 38th Annual Symposium on Foundations of Computer Science
Finding a Path of Superlogarithmic Length
SIAM Journal on Computing
Single-strip triangulation of manifolds with arbitrary topology
SCG '04 Proceedings of the twentieth annual symposium on Computational geometry
Finding paths and cycles of superpolylogarithmic length
STOC '04 Proceedings of the thirty-sixth annual ACM symposium on Theory of computing
Finding large cycles in Hamiltonian graphs
SODA '05 Proceedings of the sixteenth annual ACM-SIAM symposium on Discrete algorithms
A linear-time approximation scheme for planar weighted TSP
FOCS '05 Proceedings of the 46th Annual IEEE Symposium on Foundations of Computer Science
Optimal Covering Tours with Turn Costs
SIAM Journal on Computing
8/7-approximation algorithm for (1,2)-TSP
SODA '06 Proceedings of the seventeenth annual ACM-SIAM symposium on Discrete algorithm
An improved upper bound for the TSP in cubic 3-edge-connected graphs
Operations Research Letters
An improved strategy for exploring a grid polygon
SIROCCO'09 Proceedings of the 16th international conference on Structural Information and Communication Complexity
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We give a systematic study of Hamiltonicity of grids - the graphs induced by finite subsets of vertices of the tilings of the plane with congruent regular convex polygons (triangles, squares, or hexagons). Summarizing and extending existing classification of the usual, ''square'', grids, we give a comprehensive taxonomy of the grid graphs. For many classes of grid graphs we resolve the computational complexity of the Hamiltonian cycle problem. For graphs for which there exists a polynomial-time algorithm we give efficient algorithms to find a Hamiltonian cycle. We also establish, for any g=6, a one-to-one correspondence between Hamiltonian cycles in planar bipartite maximum-degree-3 graphs and Hamiltonian cycles in the class C"g of girth-g planar maximum-degree-3 graphs. As applications of the correspondence, we show that for graphs in C"g the Hamiltonian cycle problem is NP-complete and that for any N=5 there exist graphs in C"g that have exactly N Hamiltonian cycles. We also prove that for the graphs in C"g, a Chinese Postman tour gives a (1+8g)-approximation to TSP, improving thereby the Christofides ratio when g16. We show further that, in any graph, the tour obtained by Christofides' algorithm is not longer than a Chinese Postman tour.